Radiant panel heating appliance



March 28, 1950 GRQTHQUSE 2,502,148

RADIANT PANEL HEATING APPLIANCE Filed April 5, 1949 4 Sheets-Sheet 1Inventor: PrankTI Gr-othouse,

[ 38 flay-I y His Attorney.

March 950 F. T. GROTHOU'SE V 0 RADIANT PANEL HEATING APPLIANCE I FiledApril 5, 1949 Y 4 Sheets-Sheet 2 Inventor": Fran k-T Gr-ocho'use,

His AttorwZyi Mil-ml! 1950 F. T. GROTHOUSE 2,502,143

RADIANT PANEL HEATING APPLIANCE Filed April 5, 1949 4 Sheets-Sheet 5Inventor: FrankT Gr-t t house,

byM "W His Attqrnev.

March 28, 1950 F. T. MGROTHOUSE 2,502,148

' RADIANT PANEL HEATING APPLIANCE Filed April 5, 1949 4 Sheets-Sheet 4Irfivntor": Frank '1'. Grochouse,

.by I

l-lis Attorney.

Patented Mar. 28, 1950 UNITED RADIANT PANEL HEATING APPLIANCE Frank T.Grothouse, South Euclid, Ohio, assignor to General Electric Company, acorporation of New York Application April 5, 1949, Serial No. 85,662

Claims. 1

My invention relates to electric heating apparatus, and in particular toheating apparatus in the form of electrically heated panels for theradiant heating of an enclosed space.

In the art of heating enclosed spaces such as rooms and offices, it hasbeen demonstrated that a highly satisfactory and efficient system isprovided for warming the space and the occupants within the space byheating large areas on the surfaces enclosing the space. Such a heatingsystern has the advantage of providing uniform heat radiation to allparts of the enclosed space, and an occupant of a room so heated bylarge warmed areas on the walls, ceiling, or floor will have thesensation of warmth, even though the ambient air temperature isrelatively low, since the heated surfaces greatly reduce the rate ofradiation of heat from the body. It is therefore a primary object of myinvention to provide electrical heating apparatus in the form of thin,fiat panels which may be attached to the interior surfaces of anenclosed space, such as a room, to provide uniform radiant heating toall parts of such space.

When heating by the use of electric energy, it is desirable thatsubstantially all of the heat given off by the electrical heatingelement be used for heating the enclosed space and Warming the occupantswithin the space since, generally speaking, the cost of electricalenergy exceeds the cost of other sources of heat. It is therefore afurther object of my invention to provide electric heating panels whichprevent heat dissipation through the enclosing surfaces and direct themaximum amount of heat into the enclosed space.

Electrical panel heating systems, in order to be competitive with moreconventional types of heating apparatus, must be economical in the firstcost of the heating panels and related components necessary for acompleted installation, and must provide a construction which is readilyinstalled with the minimum of labor. Another object of my invention,therefore, is to provide an electrical heating panel construction suchthat the panels may be economically produced by mass production methods.Also an object of my invention is to provide a heating panel easilymounted on a surface, and which may be readily replaced in case offailure of the heating element or damage to any of the component parts.

A further object of my invention is to provide an electric heating panelwhich adequately protects the heating element from damage, and whichprotects the occupants of the room from contact with any of theelectrical system.

Another object of my invention is to provide a convenient constructionfor supplying electrical power to each panel.

A feature of the invention which is useful in fulfillment of theforegoing objects consists of a heating panel construction having aseparate sole plate for attachment to a surface to be heated and uponwhich power supply buses are mounted, and having a panel case quicklyattachable to the sole plate, with an electrical heating elementcompletely enclosed by the panel case and sole plate. Another feature ofthe invention is in the construction of a sole plate for the panel witha refleeting surface to minimize the loss of heat, and to reflectsubstantially all of the heat into the space being heated. A furtherfeature of this invention consists of an improved bus bar and heatingelement construction, spring contact portions of the bus bars engagingsurface contact tabs on the electrical resistance element, and the busbars extending from a power supply line to several aligned panels withspaced insulating portions at the points where the bus bars pass fromone panel to an adjacent panel.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawings, and its scope willbe pointed out in the appended claims.

Referring to the drawings, Fig. 1 illustrates a portion of the wall of aroom with several panels and bus bars installed; Fig. 2 is across-sectional view taken on the line 2-2 of Fig. 1; Fig. 3 is a planView of a heating panel, showing one embodiment of my invention, withportions of the panel cut away to show details of construction; Fig. 4is an exploded view in perspective of one form of a heating panel withbus bars in accordance with my invention; Fig. 5 is a perspective vie ofa portion of two adjacent panels with a terminal bus in position; Fig. 6illustrates a portion of a heating element for a panel in accordancewith one embodiment of this invention; Fig. 7 is an exploded view inperspective of another form of heating panel construction in accordancewith my invention; Fig. 8 illustrates a portion of a bus bar at anintermediate stage in its manufacture; Fig. 9 illustrates the completedbus bar shown. by Fig. 8; Fig. 10 illustrates in perspective one of thestruck-up projections on the sole plate for the mounting of the panelcase; Fig. 11 is a plan view, with surfaces partially broken away, of acompleted panel made in accordance with the embodiment shown by Figs. '2through 10; Fig. 12 is a cross-sectional view taken on the line l2--i2of Fig. 11; Fig. 13 is a crosssectional view taken on the line l3--l3 ofFig. 11.

Referring to the drawings, a portion of a completed installation isshown by Fig. 1 with a plurality of radiant heating panels I installedon a wall 2 of a room or other enclosed space. A conventional base board3 extends along the lower part of wall 2, it being understood that thisbaseboard may be in the form of a conduit for conhealing electricalpower supply lines through which electrical power is supplied to theheating panels I.

The details of the construction of each panel and of the bus bars forsupplying power to each panel will be more readily apparent by areference to Figs. 2 through 6. For attaching the panels to a surface,each panel has a sole plate 4, shown in detail by Figs. 4 and 5. Soleplate 4 may be attached or fixed to the surface to be heated by anysuitable fastening devices, such as nails or screws passing throughapertures 5 into Wall 2. The sole plate 4 is made preferably of metal,so that it will have the requisite strength and rigidity; and itsoutward surface, the surface away from the Wall upon which the panel ismounted, is given a bright polished finish, so that the heat from anelectrical resistor within the panel will be reflected outwardly andwill not be dissipated through the sole plate into wall 2. Along twoopposite edges of sole plate 4, a series of struck-up clips or latchesii are provided for the ready assembly of the panel case to the soleplate as will be more fully explained later. The clips 6 on sole plate 4may be formed by a simple punching and stamping operation. But bars Iand 8 are anchored to the sole plate 4, and for this purpose ears 9 andH] are struck-up from sole plate 4 near each corner. The cars 9 and 10may be bent inwardly to form clips for anchoring the bus bars inposition.

As an aid in aligning adjacent panels with one another, one edge of eachsole plate 4, such as the lower edge, is provided with a slightly ofisetflange H. The amount of the offset for flange l l is the thickness ofthe sole plate, so that each sole plate can be in firm contact with thesurface upon which the panels are mounted. Along the edge oppositeofl'set flange ll, notches l2 and K1 are provided at the corners. Thus,as shown in Fig. 5, with the lower panel sole plate in position and thenotched corners l2 and i3 along its upper edge, the next adjacent soleplate 4 may be mounted above with its offset flange H overlapping thesole plate of the lower panel, and the corners of the upper panel willlie within notches l2 and I3 to insure proper alignment.

After all of the sole plates for the entire installation have beenmounted in position, the bus bars for supplying power to each panel areinstalled. Each bus bar is in the form of a continuous strip ofresilient electrical conducting material, such as phosphor bronze. Instellations where the heating panels are installed on a wall, the busbars extend from the lower edge of the lowermost row of panels to theupper edge of the top row of panels and connections may be made to thepower supply lines at either the lower or upper edge. Two bus bars I and8 are associated with each row of panels so that the heating elements ofthe panels are connected in parallel. Therefore if there is a failure ofthe electrical circuit in any one panel, this will not affect the supplyof power to adjacent panels.

At spaced points along each bus bar, it is an closed within an insulator[4, The spacing of insulators l4 corresponds to the panel dimensions sothat each bus bar is completely insulated at tially through the thepoint where it extends from one panel to the next adjacent panel.Insulator I4 may be made up from two plates of insulating materialpreformed to the proper shape, with one plate applied to each side ofthe bus bar; or insulator I4 may be of a suitable thermo-setting plasticmolded in position on the bus bar. Anchor holes I5 are provided for thereception of a rivet or other fastening device to anchor the bus bar tothe insulator. Such anchor holes are not essential, however, ifinsulator I4 is molded in position. Between the insulators I 4, each busbar is provided with a bowed portion, and it is this portion of the busbar which makes contact with the heating element.

In the assembly of the bus bars on the installed sole plates 4, apreformed insulator IB is mounted on the sole plate for each of the busbars. Insulator l6 preferably is of heavy impregnated paper with itsintermediate portion in the form of a channel having flanges I1 and I8projecting outwardly from the exposed face of sole plate 4. This channelportion is adapted to receive the exposed intermediate portion of eachbus bar to insure that the bus bar is insulated from the metal soleplate. After insulating channel l6 has been mounted on the sole plate,the bus bar with its insulators assembled thereon is ready forinstallation. Each insulator I4 is provided with notches l9 and 20adjacent each end. The bus bar is placed in position on the sole plates4 with the series of notches l9 and 29 in alignment with and under thepairs of struck-up ears 9 and H). Ears 9 and I0 thus anchor the bus barassembly in position. Notches 2| are provided in the offset flange ll oneach sole plate so that the bus bar insulator I4 may lie in contact withthe face of sole plate 4 at the point where the insulator extends fromone panel to an adjacent panel.

In the embodiment shown in Figs. 2 through 6, the electric heatingelement 22 is constructed by cementing a layer of metallic foil 24, suchas lead foil, to an insulating backing 25, and cutting the legs of agrid through the foil and parinsulating backing. The completed heatingelement 22, the back side of which is shown by Fig. 4, is illustrated indetail by Fig. 6. When the layer of metallic foil 24 is cemented to thebacking 25, contact tabs 23 are folded over onto the back side of theinsulating backing, and these contact tabs 23 are adapted to contact thebus bars 1 and 8 for the supply of electrical power to each heatingelement. To form the heating grid, a slitting cutter, such as a45-dcgree cutter, is used to slit the foil 24, each cut starting from anedge of the foil and extending to a point slightly short of the oppositeedge of the foil. The cuts are made starting from alternately oppositeedges of the foil, thus forming the legs of the heating grid. Theslitting cutter is set to out completely through the foil 24 andpartially through the insulating backing 25 upon which this foil ismounted. For additional protection of the layer of metal foil 24, it ispreferable to cement to the surface of the grid an insulating sheet ofthermoplastic, which upon application of heat and pressure will fill theslots 26 to maintain the slit edges of the foil permanently separated.By such aconstruction an easily fabricated and low cost heating elementis provided which is readily mounted within the heating panel.

In accordance with this construction practically all of the installationwork is performed without handling the heating elements 22 or theheating panel case 28, since the sole plates and bus bars are installedin proper position before the heating elements or the panel cases areattached. Prior to the mounting of heating element 22 on sole plate 4,it is preferable to place an insulating board 21 over the exposedsurface of the sole plate. The insulating board 21 serves as anadditional protective element to prevent a short circuit from theheating element to the sole plate and also to provide additional heatinsulation to prevent loss of heat to the wall surface. The insulatingboard 21 should be of a proper thickness to maintain the heating elementin proximity with the inside of the panel case as will appear later.

After the sole plate has been mounted on the wall surface, the bus barshave been installed, and the insulating board 21 is in position, heatingelement 22 is placed over the sole plate and insulating board with thecontact tabs 23 on the back side of heating element 22 so oriented as tomake contact with the bowed portions of bus bars I and 8. Uponattachment of the cover 28 to sole plate 4 the panel is then in itscompleted form.

The panel case or cover 28 is in the form of a shallow pan having apanel surface portion 29. Along two opposite sides of the case 28,narrow side walls 30 are provided, and extending from each side wall isan inwardly directed lateral flange 3| bent over from the side wall.These lateral flanges 3| have a series of elongated apertures 32 whichcooperate with the struck-up latches or clips 6 on the sole plate formounting of the panel case 28 on the sole plate. The lower edge of thepanel case, as shown by Fig. 4, is provided with a narrow wall portion33 having spaced outwardly extending flanges 34. Along the upper edge ofpanel case '28, a narrow wall portion 35, notched out at spacedintervals as shown at 36 is provided. Adjacent each notched out portion36, the narrow side wall 35 has an inwardly extending lateral flange 31.Thus the upper edge of the panel case, shown by Fig. 4, is adapted toreceive outwardly extending flanges 34 along the lower edge of a panelcase installed next above, with the outwardly extending flanges 34 ofthe upper case fittin in the notched out portions 38 of the lower case,to insure proper alignment of the panel cases.

In final assembly, a case insulator 38 is employed between the metalliclayer 24 of the heating element and the inside of the panel case 29 toeffectively insulate the heating element from the case. This insulatormay be of any suitable material such as pressboard, impregnated with asuitable insulating compound. As an alternative arrangement, the panelcase and heating element may be prefabricated as a unit, so that whenthe sole plate and bus bars are installed, this unit can be attached tothe sole plate to complete the panel.

After all of the heating panels have been installed on any givensurface, connections are made from an electrical supply line, not shown,to the bus bars 1 and 8 to supply electrical power to each panel.

In Figs. 7 through 13, I have shown an alternative embodiment of myinvention. In particular, in Fig. 7 the principal components of theheating panel are sole plate 39 with bus bars 40 and 4| thereon, aheating element 42, and a panel case 43. The completed panel appears asshown by Fig. 11 with the various portions of the panel broken away toshow the details of construction.

Referring in particular to the sole plate 39, it is fabricated fromsheet metal cut to an appropriate size corresponding to the desiredpanel size and shape. These panels may be made in any size or shape;however I have found it desirable to employ a rectangular configuration,and by using a panel approximately 16 inches square, the desiredflexibility is achieved so that such panels may be readily adapted toany given installation. After sole plate 39 has been cut to the propersize, it is placed in a press and embossed portions 44, 44a, 45 and 45aare formed, raising these portions up from the exposed surface or faceof the sole plate as it is mounted on a wall or other surface. Withinthe embossed portion 44 and 44a, spaced areas 46 are not embossed, andhence there areas 46 appear as depressions on the exposed face of thesole plate. The embossed portions 44, 45 and 45a form a channel on thesole plate to receive the bus bar 40; and likewise the embossed portions44a, 45 and 45a form a channel for bus bar 4 l. A further purpose of theembossed portions, particularly the portions 44 and 44a, is to reducethe amount of insulation required between the sole plate 39 and theheating element 42. The depressed portions 48 serve to increase therigidity of sole plate 39 and also to increase the surface area on theback side of the sole plate so that it will rest firmly on the wall orsurface upon which the panel is mounted. Sole plate 39 is also providedwith a series of apertures 41, through which fastening devices such asscrews or nails may pass for mounting the sole plate on the wall. Thepreferred form for the mounting apertures 41 is best shown by Fig. 12.The edge portion 49 of sole plate 39 is bent over on itself to provide adouble thickness of metal around the edges of the sole plate. With thisconstruction, aperture 4! may be provided with a portion of increaseddiameter to receive the head of the screw or nail 49. Thus the exposedsurface of the sole plate is free from objectional projections whichwould otherwise result from the exposed heads of the fastening devices.

The bus bars 49 and 4!, encased by insulation 50 and SI, are held inposition on the sole plate by clips which form a part of the sole plate.Each of these clips consists of a pair of cars 52 and 53 struck up fromthe sole plate. In a completed installation, the bus bars 40 and 4|extend from a power supply source through a plurality of panels. Forconvenience it is preferable to fabricate the bus bars in a continuousstrip so that sections of appropriate length may be cut at the point ofinstallation. Referring to Figs. 8 and 9, each bus bar is made from aconducting strip of resilient material 40 encased in insulation 59. Ithas been found that phosphor bronze is a suitable material for theconductor 40, and the insulation is preferably of plastic which may beextruded. In the process of extrusion of the bus bar 49 and theinsulation 58, a cam actuated guide may be used to periodically bringthe conductor 49 to the outside of the insulation. in order to providean exposed contact surface. Assuming that the bus bars are beingfabricated for use with heating panels 16 inches square, in themanufacture of the bus bar, the conductor will be brought to the surfaceof the insulation at sixteen inch intervals. The bus bar contactportions 54 which are thus exposed should have a length of approximately 2 inches. After the extrusion process, the exposed portion54 of bus bar 40 is bowed upwardly, as shown by Fig. 9, to provide aresilient contact portion.

In this embodiment, any type of resistance element may be used which isin the form of a thin fiat plate with a conducting film or layer on oneside, and electrical contact portions on the other side. It has beenfound that a highly satisfactory element results from the use ofgraphite flakes in a silicone resin sprayed as a film on an insulatingboard. In the embodiment shown by Figs. 7 through 13, a board 57, offiber or other insulating material, is employed and contact strips 55and 56, of brass wire cloth or other suitable conducting material, aresewed along two opposite edges of the insulating board 51. Theconducting film 58, of graphite-flakes or powder in a silicone resin, isthen sprayed on one surface of the insulating board 51. The strips 55and 56 of brass wire cloth provide the means for conducting electricalpower to the conducting film 58, and the lower ends of strips 55' and 56are folded over and fastened along the surface of insulating board 51opposite conducting film 58. The ends of brass wire strips 55 and 56 arelocated and mounted on the back side of the insulating board to providethe contact portions 59 and 60. A thin layer of insulating material SIis cemented over the conducting film 58, and likewise a thin layer ofinsulating material 62 is cemented over the other surface of theinsulating board. The insulating layer 82 on the back side, that is theside away from the conducting layer, of insulating board 51 has slots 63and 64 provided therein for the mounting of the contact strips 59 and69. Thus the completed element 42 consists of a resistor in the form ofa thin layer of conducting material completely enclosed betweeninsulating sheets, with two surface contacts 59 and 6B exposed on oneside. The exposed contacts 59 and 68 of heating element 42 are solocated that when heating element 42 is mounted on sole plate 39,exposed contacts 58 and til will be contacted by resilient portions 54of bus bars 40 and 4|.

The completed heating panel is enclosed and protected by panel case orcover 43 corresponding in size and shape to sole plate 39. After thesole plate has been mounted on a wall or other surface, and bus bars 40and 4! have been attached to the sole plate by clips 52 and 53, heatingelement 42 and panel case 43 may be readily mounted on sole plate 39.The panel case 43 is in the form of a shallow pan having a surfaceportion 65, which forms the surface of the panel. Narrow side wallportions 66 are bent up from surface portion 65, and inwardly extendingflanges 61 are bent over from side walls 56, with attaching flanges Elsubstantially parallel to surface portion 65 of panel case 43. Along theupper and lower edges of panel case 43, notches 68 and 69 are providedin. side walls 88 and flanges 61 for the reception of bus bars 40 and4|. The panel case 43 and sole plate 39 are arranged so that the casemay be placed in position with re spect to the sole plate, and by asimple movement case 43 is engaged by latches on sole plate 39 to lockthe case in position. Along the upper edge of sole plate 39 a pair ofcatches in and H are provided which cooperate with a pair of elongatedslots 12 and 13 along the upper edge of panel case 43. Similar catchesl4, l5, and 16 may be provided along the lower edge of sole plate 39 forengagement with slots, not shown, along the lower edge of panel case 43.

Along the side edges of sole plate 39, as shown in Fig. '7, a series oflatches 11 are provided for engagement with corresponding notches 18provided along the inwardly extending flange 61 of panel case 43. Theform of latches I1 is best shown by a reference to Fig. 10. Latch 11 isstruck-up from the material forming sole plate 39 and it is designed tofacilitate engagement of notches 18 with latches T! when the panel case43 is moved downwardly to lock it in position. Each latch has a flatportion 19 which is substantially parallel with the face of sole plate39 and is sufiiciently spaced therefrom to receive the inwardlyextending flange 61 of the panel case 43. The flared portion of latch 11serves as a guide when panel case 43 is being moved into the engagedposition. A side wall BI is provided for latch 11 to provide the properlateral alignment between panel case 43 and sole plate 39; and a bottomwall 82 is provided for the vertical alignment.

In both of the embodiments described above, an electrical heating panelconstruction is provided which is readily mounted on a wall or othersurface with the minimum of labor in accomplishing the completedinstallation. The panel sole plates alone are first mounted on thesurface. Therefore at this stage of the assembly, it is unnecessary tohandle heating element 42 or panel case 43. No special fitting oron-thejob alterations are required in mounting of the sole plate, sinceeach sole plate is of a uniform size and each sole plate simply may benailed or screwed in position. Once the sole plates have been attachedto the surface upon which the panels are being installed, the bus barsmay be tied in to the power supply line, and only two bus bars areneeded for any series of panels in a given row. The bus bars are readilyainxed to the sole plate since the sole plate has been prefabricatedwith the upstanding ears in position for engagement with the insulatedportions of each bus bar. The panel heating element and panel case foreach panel are then ready for installation. No special attaching meansare necessary for the mounting of the heating element since it is heldin position within the enclosure formed by the sole plate and the panelcase; and no special connections are required between the bus bars andthe heating element since whenever the heating element is mounted inposition contacts are automatically made between the bus bars and theterminals of the heating element. The panel case is mounted on the soleplate with the minimum of time and labor. It is merely necessary toplace it in its proper position overlying the sole plate, and then by aslight movement, the cooperating latches on the sole plate and the panelcase are engaged to maintain the entire assembly as a unitary heatingpanel.

While I have shown particular embodiments of the various phases of myinvention, it will be understood, of course, that I do not wish to belimited thereto, since modifications may be made and I, therefore,contemplate by the appended claims to cover any such modifications asfall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An electric heating panel comprising a sole plate attachable to asurface, said sole plate having two sets of struck-up clips on the sideaway from said surface, an insulated heating element with terminalsthereon, a cover cooperating with said sole plate to enclose saidheating element,

9 said cover having apertures cooperating with said one set of clips toattach said cover to said sole plate, and means for supplying power tosaid terminals, said means being attached to said sole plate by saidother set of clips.

2. An electric panel heater comprising a resistor in the form of a thinlayer of conducting material on one surface of an insulating backing,contact tabs for said resistor exposed on the other surface of saidbacking, a sole plate attachable to the surface to be heated forsupporting said panel, bus bars affixed to and insulated from said soleplate, an insulating sheet covering said layer of conducting material,and a case attachable to said sole plate for enclosing said resistor andsaid bus bars, said bus bars contacting said tabs and extending outsidesaid case for connection to a power supply source.

3. In electric heating apparatus of the panel type, a bus bar adapted tocontact a surface ter- M minal of the heating element in each of aplurality of such panels, said bus bar comprising an insulatedconductor, said conductor having exposed resilient portions extendingoutside said insulation at longitudinally spaced points formingcontacting elements to contact said surface terminals.

4. In an electric heating panel having an enclosing case and bus barsextending through said case and insulated therefrom, a heating elementreceivable Within said case comprising an insulating board, and a thinlayer of metallic foil secured to one side of said board with contacttabs on the other side thereof, said foil being out along spacedparallel lines alternately from opposite edges substantially completelyacross said foil to form a long continuous electric circuit, said tabsmaking contact with said bus bars when said heating element is mountedwithin said case.

5. An electric heating panel comprising a sole plate attachable to asurface to be heated and having a heat reflecting finish on its sideaway from said surface, two sets of clips on said side of said soleplate, bus bars afiixed to said sole plate by one set of said clips,said bus bars having portions thereof enclosed by insulation and exposedintermediate resilient portions, a heating element including a layer ofmetallic foil cemented to one side of an insulating backing, said foilbeing slitted from alternately opposite edges thereof to form a longcontinuous electrical circult, means for making contact between saidfoil and said bus bar resilient portions, and a panel case having apanel surface portion and narrow side wall portions, said narrow wallportions including means cooperating with said second set of clips forattachment of said panel case to said sole plate, whereby said heatingelement is enclosed by said sole plate and said panel case, said busbars extending outside said panel for connection to a power source.

6. In an electric heating panel including a panel housin and powersupply means supported by said housing, a heating element comprising asheet of insulation, conducting strips attached along two opposite edgeson one side of said sheet and extending to the other side of said sheet,a conducting film on said one side, an insulating layer over said filmsubstantially coterminous with said sheet, and a second insulating layercovering said other side of said sheet and said strips, said secondlayer having apertures to expose portions of said strips to provideterminals 16 for said heating element, said heatin element be ingconstructed and arranged to be supported Within said housing with saidexposed portions making contact with said power suppl means.

7. In an electric heating panel, a heating element having terminalsthereon, bus bars for contacting said terminals and a housing supportingsaid bus bars and enclosing said heating element, said housingcomprising a sole plate attachable to a surface for mounting said panel,said sole plate including embossed portions on the face thereof formingrecessed channels for said bus bars, latching members on said soleplate, and a shallow pan-shaped cover having a surface portion andnarrow side wall portions with inwardly directed flanges thereon, saidflanges having slots cooperable with said latching members for attachingsaid cover to said sole plate, said cover and said sole plate supportingsaid heating element therebetween when assembled.

8. In an electric heating panel, a heating element having terminalsthereon, bus bars for contacting said terminals, and a housingsupporting said bus bars and enclosing said heating element, saidhousing comprising a sole plate attachable to a surface for mountingsaid panel, latching members on said sole plate, and a shallowpan-shaped cover having latching members adapted to cooperate With saidsole plate latchin members.

9. An electric heating panel comprising a sole plate attachable to asurface to be heated, said sole plate having embossed portions on theface thereof and forming recessed channels thereon, latching members onsaid face, bus bars receivable within said recesses, means on said soleplate for afiixing said bus bars thereto, each bus bar comprising aconductor having longitudinally spaced portions enclosed by insulationwith exposed conductive portions interspersed therebetween, a heatingelement having a conducting film on one side and surface terminals onits 0pposite side, said terminals being oriented to contact said exposedportions of said bus bars when said element is positioned overlying saidsole plate, a shallow pan-shaped cover having a panel surface portionand narrow wall portions with inwardly directed flanges on said wallportions, said flanges having slots engageable with said latchingmembers, whereby said cover may be afiixed to said sole plate to enclosesaid positioned element.

10. Electrical heating apparatus of the panel type comprising a, heatingelement sealed between insulating layers with contact tabs exposed onthe surface of one layer, a sole plate attachable to a surface formountin said panel, said sole plate having a heat reflecting side awayfrom said surface, resilient bus bars supported on and insulated fromsaid side and oriented to establish electrical contact with said tabs,and a panel case attachable to said sole plate, said heating elementbeing supported within said case with said one layer adjacent said heatreflecting side of said sole plate and said other layer adjacent saidcase.

FRANK T. GROTHOUSE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,954,773 Champion et a1. Apr.10, 1934 2,418,557 Reiser Apr. 8, 1947

